# 不能想list那样通过索引来访问
names = ['John', 'Jane', 'George']
name_sets = set(names)

print('John' in name_sets)
print('Alice' in name_sets)

# 遍历
for name in name_sets:
    print(name)

# 使用集合推倒，转变成大写
original_set = {'John', 'Jane', 'George'}
uper_set = {s.upper() for s in original_set}
print(uper_set)